Research interest:I am currently working with an orchid lectin known as the Gastrodia anti-fungal protein, or GAFP. GAFP has shown inhibitory activity against multiple species of plant pathogenic fungi (Hu and Huang, 1994), and our lab has recently shown that GAFP is active against non-fungal plant pathogens as well. In transgenic tobacco and plum, expression of the GAFP lectin provided increased tolerance to an endo-parasitic root-knot nematode (RKN), as well as oomycete pathogens causing Phytophthora Root Rot (Cox et al., 2006, Nagel et al., 2008). Up to this point, GAFP had been characterized primarily as an anti-fungal agent, but our work is the first to show that GAFP may have activity against non-fungal organisms. The inhibitory mechanism of this lectin towards non-fungal pathogens has not been investigated. Elucidating more about the mechanism of GAFP is important in order to further clarify the mode of action of a lectin which has potential for agricultural application. This is the goal of my Ph.D. thesis.
We have observed the effects of GAFP on plant pathogens indirectly through the monitoring of disease development in our transgenic tobacco and plum lines. Because of our novel findings in the greenhouse, we feel it is important to confirm the direct action of GAFP on the RKN and Phytophthora species under controlled conditions. Additionally, we plan to use immunofluorescence microscopy on these pathogens in order to identify the sites of action of GAFP within the cell. A second objective of my research is the determination of GAFP's binding specificity. Proteins related to GAFP are known to bind mannose and mannose-derived residues (Van Damme et al., 1998). Past research has indicated that GAFP may also be able to bind another saccharide residue, N-acetylglucosamine (Xu et al., 1998), however this activity has never been thoroughly investigated. The ability to bind different saccharide residues could contribute to this lectin’s broad-spectrum activity against plant pathogens, due to variations in cell wall polysaccharide composition among different organisms.

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